fission

noun
fis·​sion | \ ˈfi-shᵊn How to pronounce fission (audio) , -zhᵊn\

Definition of fission

 (Entry 1 of 2)

1 : a splitting or breaking up into parts
2 : reproduction by spontaneous division of the body into two or more parts each of which grows into a complete organism
3 : the splitting of an atomic nucleus resulting in the release of large amounts of energy

fission

verb
fissioned; fissioning; fissions

Definition of fission (Entry 2 of 2)

intransitive verb

: to undergo fission

transitive verb

: to cause to undergo fission

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Other Words from fission

Noun

fissional \ ˈfi-​shə-​nəl How to pronounce fissional (audio) , -​zhə-​ \ adjective

Examples of fission in a Sentence

Recent Examples on the Web: Noun

This process, nuclear fission, generates heat that is directed to a cooling agent—usually water. National Geographic, "What is nuclear energy and is it a viable resource?," 26 Mar. 2019 Often, this energy comes from a process called fission, when a neutron rams through an atom’s nucleus, splitting it. John Wenz, Discover Magazine, "NASA's New Nuclear Reactor Could Change Space Exploration," 11 Feb. 2019 There's that whooshing groundswell where the powerful forces of food, society, upscale retail and anticipation collide in the cultural fission chamber that is Houston. Greg Morago, Houston Chronicle, "MAD: A sensory ambush arrives at River Oaks District," 19 June 2019 The goal is to remove unwanted U-238 isotopes from the uranium and increase the proportion of U-235 to a level necessary for nuclear fission. Nicholas Wu, USA TODAY, "What to know about Iran's uranium enrichment program," 17 June 2019 Meanwhile, per capita carbon emissions in France, which generates three-quarters of its electricity from nuclear fission, are roughly half those of Germany. Charles Lane, Twin Cities, "Charles Lane: If Germany wants to achieve climate neutrality, it needs nuclear power," 5 June 2019 Fusion could deliver more energy more safely and with far less harmful radioactive waste than fission, but just a small number of people—including a 14-year-old from Arkansas—have managed to build working nuclear fusion reactors. National Geographic, "What is nuclear energy and is it a viable resource?," 26 Mar. 2019 Known as the fission hypothesis, Darwin’s idea was that the moon began as a chunk of Earth and was hurled into space by the Earth’s rapid rotation, leaving behind the Pacific basin. David Warmflash, Smithsonian, "An Ancient Greek Philosopher Was Exiled for Claiming the Moon Was a Rock, Not a God," 8 Oct. 2014 Iodine-131 is a byproduct of nuclear fission like what is used in nuclear weapons. Kyle Mizokami, Popular Mechanics, "Report Says European Mystery Radiation Isn't Real. That Isn't Stopping an Air Force Investigation.," 22 Feb. 2017

Recent Examples on the Web: Verb

The point is that by analyzing the array of radioactive fission products – those that can be captured and analyzed – nuclear forensic specialists can start to figure out if the atoms that fissioned were U-235, Pu-239, or (in some cases) U-238. Andrew Karam, Popular Mechanics, "Nuclear Forensics: How Scientists Can Tell Whether North Korea Is Lying About Its Bomb Test," 7 Jan. 2016 Anyone can see that fissioning uranium 235 or plutonium can be used to generate electricity. Scientific American, "Readers Respond to the January 2018 Issue," 1 Jan. 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'fission.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of fission

Noun

circa 1617, in the meaning defined at sense 1

Verb

1929, in the meaning defined at intransitive sense

History and Etymology for fission

Noun

borrowed from Latin fissiōn-, fissiō, from fid-, variant stem of findere "to split, cleave" + -tiōn-, -tiō, suffix of verbal action — more at bite entry 1

Verb

derivative of fission entry 1

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Statistics for fission

Last Updated

13 Jul 2019

Look-up Popularity

Time Traveler for fission

The first known use of fission was circa 1617

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More Definitions for fission

fission

noun

English Language Learners Definition of fission

physics : a process in which the nucleus of a heavy atom is split apart
biology : a kind of reproduction in which a cell or body divides into two or more parts and each part grows into a whole new individual

fission

noun
fis·​sion | \ ˈfi-shən How to pronounce fission (audio) \

Kids Definition of fission

1 : a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual
2 : the process of splitting an atomic nucleus with the release of large amounts of energy

fission

noun
fis·​sion | \ ˈfish-ən also ˈfizh- How to pronounce fission (audio) \

Medical Definition of fission

1 : a method of reproduction in which a living cell or body divides into two or more parts each of which grows into a whole new individual
b : the splitting of an atomic nucleus resulting in the release of large amounts of energy

called also nuclear fission

Other Words from fission

fission verb fissioned; fissioning\ ˈfish-​(ə-​)niŋ also ˈfizh-​ How to pronounce fissioning (audio) \
fissional \ ˈfish-​ən-​ᵊl also ˈfizh-​ How to pronounce fissional (audio) \ adjective

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More from Merriam-Webster on fission

Rhyming Dictionary: Words that rhyme with fission

Spanish Central: Translation of fission

Nglish: Translation of fission for Spanish Speakers

Britannica English: Translation of fission for Arabic Speakers

Britannica.com: Encyclopedia article about fission

Comments on fission

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